Keyless entry systems are known in the art and are used, among other things, to gain access to a host of devices including automobiles, marine vehicles and garage doors. Presently available keyless entry systems include devices which have a numerical keypad located on an exterior surface or panel of, for example, the door of a vehicle or a garage. The operator enters a unique multiple digit code on the keypad to automatically unlock the vehicle or open the garage. In certain keyless entry systems, it is possible for an authorized user or customer to change the access code. However, this requires the authorized user or customer to physically input commands into the keypad. For example, U.S. Pat. No. 4,809,199 ("the '199 patent") describes a keyless marine access and engine control system having a primary and a secondary access code, either of which may be entered through a keypad to gain access to the marine vehicle. The secondary access sequence may be changed by a person who knows either the primary access sequence or the secondary access sequence. The primary access sequence can be reprogrammed through the keypad after a switch located in a secure location on the vehicle has been activated for a predetermined length of time. Thus, the primary access sequence can only be changed by a person having knowledge of both the present primary access sequence and the physical location of the reprogramming switch. Although the primary access code may be changed by an authorized user or customer, this requires (a) having an external keypad, (b) knowing the physical location of the reprogramming switch, and (c) memorizing the primary access sequence. A similar system used for automatic garage door openers is described in U.S. Pat. No. 5,252,960.
Like the '199 patent, U.S. Pat. No. 4,492,959 describes a keyless entry system having an input unit for entering either a permanent code or a user code. The input unit is generally located on the external door handle or other surface of the vehicle. Although the user code may be changed by an authorized user or customer knowing the permanent code, the permanent code is preset in the system and cannot be changed by the customer. A further disadvantage of the system described in the '959 patent is that an input device attached to the vehicle is still required.
The above-discussed patents do not disclose remote control entry systems, as opposed to key-less entry systems in that a keypad or some other input device is required to input the security code into the system. Actual remote keyless entry systems are disclosed in U.S. Pat. Nos. 5,319,364 and 5,109,221, hereinafter the '364 and the '221 patents respectively. A passive remote keyless entry system is disclosed in the '364 patent where the operator carries a portable transmitter which includes a motion sensing switch that automatically activates the transmitter whenever movement of the transmitter is sensed. The transmitter corresponds to a receiver located in the vehicle which is adapted to unlock the vehicle whenever the coded radio frequency signal or a coded optical signal is received from the transmitter.
A new transmitter identification code may be programmed into the controller by having authorized service personnel ground the "program" input line, and then bring the transmitter within range of the receiving antenna. The identification code from the transmitter is then automatically read by the microcomputer into the EEPROM. Therefore, if a transmitter is lost, a new transmitter with a different identification code can be provided and the new transmitter identification code programmed into the receiver/controller by authorized service personnel. However, there is still no convenient way for an authorized user or customer to reprogram the identification code without going to the dealer and having the dealer program in the new transmitter identification code.
The remote control system disclosed in the '221 patent is similar to the '364 patent, but without the "passive" feature. A new transmitter identification code may also be programmed into a receiver by having authorized service personnel first ground a program input line, and then depress any function switch on the transmitter. Like the '364 disclosure, the '221 invention, suffers from the same disadvantage of not being reprogrammable by an authorized user or customer in the event that the transmitter is either lost or stolen. As with the '364 patent, the '221 patent requires that the authorized user or customer return to the dealer to have a new transmitter programmed into the receiver unit of the system.